Inhibitory effects of ambient levels of solar UV‐A and UV‐B radiation on growth of cucumber

Abstract

1997, Inhibitory effects of ambient levels of solar UV-A and UV-B radiation on growth of cucumber. -Physiol. Plant, 100: 886-893.The influence of solar UV-A and UV-B radiation at Beltsville, Maryland, on growth and flavonoid content in four cultivars of Cucumis sativus L. (Ashley, Poinsett, Marketmore, and Salad Bush cucumber) was examined during the summers of 1994 and 1995, Plants were grown from seed in UV exclusion chambers consisting of UV-transmitting Plexiglas, lined with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or cellulose acetate to transmit UV-A and UV-B, Despite previously determined differences in sensitivity to supplemental UV-B radiation, all four cultivars responded similarly to UV-B exclusion treatment. After 19-21 days, the four cultivars grown in the absence of solar UV-B (polyester) had an average of 34, 55, and 40% greater biomass of leaves, stems, and roots, respectively, 27% greater stem height, and 35% greater leaf area than those grown under ambient UV-B (cellulose acetate). Plants protected from UV-A radiation as well (Llumar) showed an additional 14 and 22% average increase, respectively, in biomass of leaves and stems, and a 22 and 19% average increase, respectively, in stem elongation and leaf area over those grown under polyester. These findings demonstrate the extreme sensitivity of cucumber not only to present levels of UV-B but also to UV-A and suggest that even small changes in ozone depletion may have important biological consequences for certain plant species.

Solar Ultraviolet-B Radiation Increases Phenolic Content and Ferric Reducing Antioxidant Power in Avena sativa

“…We observed a 38% reduction in total biomass production of A. sativa growing under near-ambient UV-B (Figure 1) which was mainly the result of the reduction in aboveground biomass. These results agree with other studies conducted at similar [2,7,8] and higher [10,11] latitudes. The reduction in biomass does not appear to be related to reductions in tiller or leaf production (data not shown) but rather reductions in leaf elongation (Figures 2a and 2b).…”

“…Plant responses to UV-B tend to be subtle and species-specific, especially when studies are conducted outside under realistic spectral regimes. Responses to elevated and ambient UV-B include increases in DNA-damage and antioxidant response [2], alterations in plant morphology and architecture [3,4], slight reductions in chlorophyll fluorescence parameters associated with photosystem II [PSII; 5,6] and lower biomass accumulation [7][8][9][10][11]. The most common response of field-grown plants to elevated and ambient levels of UV-B appears to be an increase in concentrations of UV-absorbing phenolics [1,12,13] that may ameliorate potentially damaging UV-B before it reaches sensitive chromophores [14][15][16].…”

Effects of ultraviolet-B radiation on crop growth, development, yield and leaf pigment concentration of tartary buckwheat (Fagopyrum tataricum) under field conditions

“…When the effect of ambient solar UV-B radiation was examined in mung bean, a decrease in the leaf area development, plant height and net photosynthesis was detected (Pal et al, 1997). Comparably, Krizek et al (1997) observed that the four tested cucumber cultivars had decreases of 25.0-28.6% in biomass, 21.2% in stem height and 25.9% in leaf area under ambient UV-B radiation. Cybulski and Peterjohn (1999) reported that short-lived herbs appeared to be much more sensitive to ambient solar radiation than other plants.…”

Genomic Mutation in Lines ofArabidopsis thalianaExposed to Ultraviolet-B Radiation

“…To provide PAR (800-1000 mm/m 2 /sec), the chamber was equipped with eight evenly spaced 1000-W metal halide UV-B lamps. While metal halide lamps do not deliver the exact spectral balance of outdoor PAR, they are often used in experiments involving UV-B exposure to provide the PAR required to ameliorate UV-B-induced injury through activation of repair enzymes (Krizek et al 1997).…”